RESUMO
Recently, the design and biosynthesis of metallic nanoparticles (NPs) have drawn immense interest, but their very specific function and secondary toxic effects are major concern towards commercial application of NPs. That's why environment-friendly (nontoxic) NPs having multiple functions are extremely important. Herein, we report the mechanism of biosynthesis of mono and bimetallic (Au-Ag) alloy NPs and study their multifunctional (antioxidant, antifungal and catalytic) activity and ecotoxicological property. AgNPs exhibit phytotoxicity (at 100 µg/ml) on morphological characteristics of Lentil (during germination), while alloy and AuNPs are non-toxic (up to 100 µg/ml). In-vitro antioxidant response using DPPH methods reveals that alloy NPs (IC50 = 55.8 µg/ml) possesses better antioxidant activity compared to the monometallic NPs (IC50 = 73.6-82.6 µg/ml). In addition, alloy NPs displayed appreciable antifungal efficacy against a plant pathogenic fungus Gloeosporium musarum by structural damage to hyphae and conidia of the fungus. The catalytic performance of NPs for degradation of chlorpyriphos (CP) pesticide reveals that alloy NPs is more efficient in terms of rate constant (k = 0.405 d-1) and half-life (T50 = 1.71 d) compared to the monometallic counterparts (k = 0.115-0.178 d-1; T50 = 3.89-6.04 d). Degradation products of CP (3,5,6-trichloropyridinol and diethyl thiophosphate) are confirmed using mass spectrometry and based on that a degradation pathway has been suggested. Thus, these sustainable and ecological safe biogenic (Au-Ag) alloy NPs promise multiple applications as an antioxidant in the pharmaceutical sector, as a fungicide for disease control in agriculture, as a catalyst for remediation of toxic pollutants and in other pertinent areas.